On election night, the electoral map might suggest a solid lead for Mr. Trump that is eroded as mail ballots are canvassed. What if Mr. Trump reprises his tweet from six days after Florida’s 2018 elections? “An honest vote count is no longer possible—ballots massively infected. Must go with Election Night!” Remember Hillary Clinton’s advice this summer: “Joe Biden should not concede under any circumstances, because I think this is going to drag out.”
The fight would probably drag out in the courts. Say it’s mid-November, and absentee ballots are being counted in a key state. Although Mr. Trump retains a modest lead, mail votes are breaking 3 to 1 for Mr. Biden. Perhaps the law in this jurisdiction requires ballots to arrive by Election Day, so there’s a pile to the side of thousands of late deliveries. Some are missing postmarks, and it’s not clear when they were mailed. Thousands more have been discarded for suspect signatures, but the rejection rates are higher in urban areas.
The best way to prevent this democratic debacle is to act before things get that far. If states tighten ballot deadlines now and prepare to process mail votes before Election Day, it would cut the risk of an outcome that causes half the country to claim it’s illegitimate. With each lawsuit that puts the count into the hands of judges, this nightmare gets more likely.